1. Field of the Disclosure
The present disclosure relates generally to imaging device media sensors and methods of using the same, and more particularly to media translucence sensors and methods of using the same.
2. Description of the Related Art
Currently, most imaging devices require the user to input media type, media weight, and texture. However, most users do not adjust media settings. Of those users that do adjust settings, only a small percentage correctly classify media. Failure to correctly set media properties results in print quality defects, poor fuse grade, and higher jam rates. Also, this leads to a higher number of service calls, visits, and replacement part rates.
Incorrectly setting media weight is a major contributor to these higher failure rates. If the media weight is set too low, the printer runs too fast, transfer voltages are set too low, and fuser temperatures are set too low. If the media weight is set too high, the printer runs too slow, transfer voltages are set too high, and fuser temperatures are set too high. Poor print quality is a result along with premature hardware failures.
In particular, light weight media set at a normal or a heavy weight has a much higher likelihood to wrap a fuser, particularly, when printing higher coverage pages. Too much heat is provided and the toner hot offsets. Because the trend is towards using lighter weight media with more refined (recycled) fiber content, this problem will become more prevalent.
Additionally, heavy weight media set at normal or light weight does not adequately melt the toner and cold offset occurs. This allows unattached toner to deposit on the fuser backup roll and be carried downstream where it contaminates paper guides and creates catch points. This results in a higher likelihood for jams, fuser being wrapped by media (fuse wraps), and machine damage on subsequent jobs. Ultimately, if media is run at an improper weight setting, user satisfaction suffers.
For the detection of media class, optical sensors often strike a reasonable balance between cost, performance, speed, and footprint when compared to other alternatives. Perhaps one of the simplest optical sensor embodiments involves using a photo detector, such as a photo-transistor for measuring the intensity of a light beam, emitted by light source such as a LED, passing through a sheet of media. Unfortunately, the analog output provided by the simplest implementation is often too variable to provide much confidence in a media class determination made from a dynamic measurement taken with this sensor arrangement. The amount of transmitted light reaching the photo-transistor is a strong function of LED intensity, wavelength, and several external factors including media composition, media position, media surface roughness, media thickness, and sensor component variability. These external factors are sources of variation that must be accommodated to ensure reliable media class determinations.
Historically, sensor output variation has been addressed through judicious architectural decisions in the structure of an imaging device, the use of media staging algorithms, expensive optics, more complex camera hardware, and/or computationally intense signal processing. These solutions are often costly, unreliable, and/or inefficient.
It would be advantageous to be able to use a simple low cost photodetector and LED sensor to be able to provide dynamic reliable media class determinations of a sheet of media as it is being fed along a media feed path in an imaging device prior to being processed. It would be further advantageous to be able to use a low-cost, space-efficient optical translucency sensor that is capable of classifying media into several different categories with a very high accuracy rate without negatively impacting throughput. It would additionally be desirable to be able to adjust an operating parameter of the imaging device or a subsystem thereof based on the selected media class.